Mask and mask cushion therefor

ABSTRACT

A cushion comprises a substantially triangularly shaped frame from which extends a membrane. The membrane is spaced away from the rim of the frame, and its outer surface is of substantially the same shape as the rim. The seal forming portion thus contacts both the surface of the wearer&#39;s nose and a portion of the wearer&#39;s face. The shape of the seal forming portion is particularly suited to effectively seal the difficult region of the facial contour that is the crease between the sides of the nose and the face.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 13/067,190, filedMay 16, 2011, now U.S. Pat. No. 8,522,783, which is a U.S. applicationSer. No. 11/826,267, filed Jul. 13, 2007, now U.S. Pat. No. 7,950,392,which is a continuation of U.S. application Ser. No. 10/934,402, filedSep. 7, 2004, now U.S. Pat. No. 7,243,651, which is a continuation ofU.S. application Ser. No. 10/004,428, filed Dec. 6, 2001, now U.S. Pat.No. 6,871,649, which is a divisional of U.S. application Ser. No.09/566,806, filed May 8, 2000, now U.S. Pat. No. 6,634,358, which is acontinuation of U.S. application Ser. No. 08/791,212, filed Jan. 31,1997, now U.S. Pat. No. 6,112,746, which claims priority to AustralianApplication No. PO 1265, filed Jul. 26, 1996, each incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The invention relates generally to a nasal mask and to a cushiontherefore, for example, for use in the treatment of respiratoryconditions and in assisted respiration.

BACKGROUND OF THE INVENTION

Nasal masks are commonly used in the treatment of respiratory conditionsand sleep disorders (e.g., obstructive sleep apnea) by delivering a flowof breathable gas for, or to assist patient respiration. These nasalmasks typically receive a gas supply line which delivers gas into achamber formed by walls of the mask. The walls usually are semi-rigidand have a face contacting portion including an aperture which isaligned with the wearer's nostrils. The face contacting portion cancomprise a soft, resilient elastomeric material which may conform tovarious facial contours. The mask normally is secured to the wearer'shead by straps. The straps are adjusted to pull the mask against theface with sufficient force to achieve a gas tight seal between the maskand the wearer's face. Gas is thus delivered to the mask and through theaperture to the wearer's nasal passages.

Problems often arise with masks of the above configuration. For example,the mask may be dislodged, thereby breaking the seal between the maskand wearer. This may occur if the wearer rolls over when sleepingthereby creating a drag force on the gas supply line which istransmitted to the mask, breaking the seal. In the case of a mask beingused for the administration of Continuous Positive Airway Pressure(CPAP) treatment for the condition obstructive sleep apnea, such a leakcan result in the pressure supplied to the entrance of the wearer'sairway being below the therapeutic value, and the treatment becomingineffective.

Another problem is that the face contacting portion may apply excessivepressure to the wearer's face resulting in discomfort and possibly skinirritation. This can occur because the face contacting portion has todistort beyond its normal range of elasticity to conform to certainfacial contours which requires the application of excessive forces. Insome cases these excessive pressures and forces may cause the face todistort to conform with the face contacting portion to increase wearer adiscomfort, facial soreness and ulceration.

Other types of devices exist whereby small nostril nosepieces (pillows)are held in place by a harness scrapped over the wearer's head, forexample as shown in prior art U.S. Pat. No. 4,782,832 (Trimble et al).While this arrangement may alleviate some problems regarding sealbreakage and skin abrasion, the harnesses associated with such devicesare quite cumbersome for the wearer, as are the gas supply lines. Also,air ‘jetting’ into the nostrils can be irritating to the patient makingsuch devices generally uncomfortable to use.

A further example of the prior art also is disclosed in U.S. Pat. No.5,243,971 (Sullivan et al).

Cushion masks have also been developed. These cushion masks have aninflated cushion which provides comfort to the wearer. However, thesemasks, under certain circumstances, may form a tuck or pucker resultingin a leak.

It is an object of the invention to overcome or at least substantiallyameliorate one or more of the foregoing disadvantages.

SUMMARY OF THE INVENTION

In one broad form, the invention discloses a nasal mask cushion tosealingly connect a mask to a wearer's face, the cushion comprising:

a substantially triangularly-shaped frame of resilient material having arim to surround wearer's nose;

a membrane also of resilient material, said membrane being relativelymore flexible than said frame, and being of the same general shape assaid rim and fixed to and extending away from said frame so as to havean outer surface spaced from said rim, a portion of said outer surfaceforming a face contacting seal; and

a nose-receiving cavity bounded by said frame and said membrane;

and wherein said seal portion is generally coterminous with respect tosaid rim and is resiliently deformable towards said rim in use of saidcushion.

In one particularly advantageous form, the membrane is substantiallysaddle-shaped. The membrane further has a centrally located aperturethrough which the wearer's nose passes to enter said cavity.

It is preferred that the cushion and membrane each include a co-locatednotch to accommodate the bridge of the nose of the wearer. Typically,the seal portion contacts at least the wearer's nose, and preferably,also the facial tissue around the sides and over the bridge of the noseand between the base of the nose and the top lip.

The invention further discloses a nasal mask for connection to awearer's face comprising:

a mask body for connection with a supply of breathable gas; and

a nasal cushion, the body and cushion defining a nose-receiving cavity,said cushion including:

a substantially triangularly-shaped frame of resilient material having arim to surround said wearer's nose;

a membrane also of resilient material, said membrane being relativelymore flexible than said frame, and being of the same general shape assaid rim and fixed to and extending away from said frame so as to havean outer surface spaced from said frame, a portion of said purer surfaceforming a face contacting seal;

and wherein said seal portion is generally coterminous with respect tosaid rim and is resiliently deformable towards said rim in use of saidmask.

The mask body can further include attachment points from which securingstraps can be attached, and by which the mask can be secured to thewearer's head. The nasal mask can yet further comprise an arm dependingfrom said body from which a further securing strap(s) can be attached.

The invention further discloses nasal CPAP treatment apparatuscomprising a flow generator for the supply of gas at a pressure elevatedabove atmospheric pressure to a gas delivery conduit, the conduit inturn coupled to a nasal mask as described immediately above.

In one particularly preferred form, a supply of gas can be provided tosaid cavity, said supply of gas assisting, but not solely causingmaintenance of a seal by said seal forming portion of said membrane tothe face of the wearer in use of the cushion.

Advantageously, the membrane and the rim are substantially shaped to thefacial contour, and the membrane does not need to turn in on itself thuscontacting the face without folds or creases. With the cushion/masksecured to the wearer's head, the headstraps need only to be tensionedto balance the force due to mask gas pressure that tends to lift themask off the face. Such relatively lower mask-to-face pressure resultsis in greater patient comfort, and a reduction in the likelihood of skinirritation.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described with reference tothe accompanying drawings, in which:

FIG. 1 is a rear perspective view of a mask cushion embodying thepresent invention;

FIG. 2 is a cross-sectional view along line 2-2;

FIG. 3 is a perspective view of a nasal mask including the cushion ofFIGS. 1 and 2;

FIG. 4 is a perspective view of the nasal mask of FIG. 3 secured to awearer's head;

FIG. 5 is a side view of the mask cushion;

FIG. 6 is a front view of the mask cushion;

FIG. 7 is a rear view of the mask cushion;

FIG. 8 is a sectional view along section lines 8-8 of FIG. 7; and

FIG. 9 is a sectional view along section lines 9-9 of FIG. 7.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a perspective view of a nasal cushion 30 embodying theinvention. FIG. 2 shows the cross-sectional view along line 2-2.Referring to FIGS. 1-2 and 5-9, the cushion 30 comprises a substantiallytriangularly shaped frame 32 from which extends a membrane 34. The frame32 has a scalloped edge 36 by which the cushion 30 is affixed to a maskbody, as presently will be described.

The membrane 34 has an aperture 38 into which the wearer's nose isreceived in use of the cushion 30. The membrane 34 is spaced away fromthe rim 40 of the frame 32, and its outer surface 41 is of substantiallythe same shape as the rim 40. The outer surface 41 of the membrane 34and the rim 40 of the frame 32 also can be described as generally saddleshaped. The shaping of the outer surface 41 of the membrane 34 and therim 40 of the frame 32 also include respective notches 42, 44 thatreceive the bridge of the wearer's nose in use of the cushion 30.

As is best seen in FIG. 2, the frame 32 and the membrane 34 areintegrally formed, typically by in a one-shot molding process. The frame32 and the membrane 34 are fabricated from a resilient material. Onesuitable such material is SILASTIC™ silicone elastomer manufactured byDow Corning. The frame 32, is one preferred embodiment, has a typicalthickness at its rim 40 of 1.5 mm. The membrane 34, in a preferredembodiment, has a typical thickness of 0.35 mm. In this way, themembrane 34 is relatively more flexible than the rim 40.

In use of the cushion 30, a wearer's nose will be inserted in theaperture 38 to engage a seal forming portion 45 (formed between thedashed lines of FIG. 3) of the outer surface 41 to cause deformation ofthe membrane 34. Depending upon the securing force supplied to themembrane 34, it may deform to a point where it butts against the rim 40of the frame 32. The frame 32 has a rigidity sufficient to withstandusual securing pressures in use of the cushion 30 to tend to retain itsshape and resist deformation. It thus acts as a supporting structure.

Referring now to FIG. 3, the nasal cushion 30 is shown attached to amask body 46 by the edge 36 of the frame 32, adhered or otherwisesecured to a flange 48 of the mask body 46. Only the outer surface 41 ofthe membrane 34 can be seen. The flange 48 includes three slots 50, 52,54 from which tensioning straps can be attached to secure the cushion 30and the mask body 46 (in combination) to the head of a wearer.

The mask body 46 forms a cavity that can receive the nose of the wearerby the aperture 38. A port 56 is provided at the top of the mask body 46by which breathable gas can be supplied to the chamber.

Referring now to FIG. 4, there is shown a nasal mask 60 including themask body 46 and the mask cushion 30. A coupling tube 62 is connected atone end with the inlet port 56, and at the other to a socket 64 intowhich can be received a gas delivery tube 65 for the supply ofbreathable gas to the chamber internal of the mask body 46. The maskbody 46 from a flow generator 67 also has two vent openings 66 by whichexpired gas is exhausted. A first fastening strap 68 is fixed between tothe lower two slots 50, 54. The upper slot 52 receives an arm 70, thetop end of which has a resilient pad 72 to engage the forehead of thewearer. The arm 70 has two slots 74 (only one slot shown in FIG. 4)along its side edges, by which a second fastening strap 78 is secured.

In fitting the nasal mask 60, the wearer's nose is received through theaperture 38 into the chamber within the mask body 46. The seal formingportion 45 thus contacts both the surface of the wearer's nose and aportion of the wearer's face in the region between the base of the noseand the upper lip, and around the sides and over the bridge of the nose.The shape of the seal forming portion 45 is particularly suited toeffectively seal the difficult region of the facial contour that is thecrease between the sides of the nose and the face. Depending upon thetension applied by the fastening straps 68, 78, a seal is formed withthe membrane 34 remaining spaced from the rim 40 of the cushion frame32. While the provision of pressurised gas to the chamber of the maskbody 46 assists in the maintenance of a seal between the membrane 34 andthe wearer's nose and face, it is not essential in most cases, and aneffective seal will be formed absent any such pressurised gas. Onrelative movement of the mask 60 in relation to the wearer's head, thenose will be restrained by contacting the frame 32. Thus only limitedrelative motion between the mask 60 and the wearer's nose and faceoccurs.

The membrane 34 closely imitates the facial contour, and because of itsrelatively lesser stiffness than the frame 32, can conform to particularfacial structures with minimum force, and without a tendency to fold orcrease.

If the fastening strap 68,78 are tensioned to excess, the membrane 34deforms to abut the rim 40 of the cushion 32, the frame 32 thus actingas an “end limit”. In such a configuration, almost zero relativemovement can occur between the mask 60 and the wearer's head.

The nasal cushion 30 and nasal mask 60 has been described with referenceto CPAP or assisted respiration treatment, however it is to beunderstood that the invention generally is applicable to any applicationwhere gas and/or atomised liquid is to be supplied to the entrance ofthe nasal airways. Such applications include nebulisers, gas masks andanaesthetic machines.

The invention claimed is:
 1. A mask cushion to sealingly connect a maskto a wearer's face, the cushion comprising: a frame of resilientmaterial having a rim to at least partially surround the wearer's nose;and a membrane also of resilient material and defining an aperture sizedto receive the wearer's nose, said membrane being thinner than andrelatively more flexible than said frame, said membrane being fixed toand extending away from said frame so as to be spaced from said rim by agap, said membrane having an outer surface forming a face contactingseal portion that is pre-shaped to generally match the contours of thewearer's face, wherein the face contacting seal portion is structuredsuch that it is not required to turn in on itself to conform with thewearer's face, in use; wherein: the cushion at least partly forms abreathing chamber to receive pressurized breathable gas, for delivery toat least a nasal passage of the wearer, the breathing chamber beingaccessible by the wearer via the aperture of the membrane; the rim andthe membrane are commonly curved towards the breathing chamber, thecushion is structured so that the pressurized gas in the chamber assistsin maintaining a seal between the membrane and the wearer in use; theframe and rim are structured to resist deformation so as to form asupport structure for the membrane, said membrane is resilientlydeformable towards said gap to abut said rim in use of said cushion; andthe rim and the membrane have a pre-formed co-located notch toaccommodate the bridge of the wearer's nose.
 2. A cushion as claimed inclaim 1, wherein said membrane and said rim are substantiallysaddle-shaped.
 3. A cushion as claimed in claim 2, wherein said membraneis shaped so that said seal portion, in use, contacts at least thewearer's nose.
 4. A cushion as claimed in claim 3, wherein said sealportion, in use, contacts the facial tissue around the sides and overthe bridge of the nose, and between the base of the nose and the toplip.
 5. A cushion as claimed in claim 1, wherein said rim and said sealportion are pre-shaped to generally match facial contours in the regionof facial tissue around the sides and over the bridge of the nose, andbetween the base of the nose and the top lip.
 6. A cushion as claimed inclaim 1, wherein the face contacting seal portion is pre-shaped toclosely imitate the contours of the wearer's face.
 7. A cushion asclaimed in claim 1, wherein the face contacting seal portion isstructured to enable contact with the wearer's face without folds orcreases.
 8. A cushion as claimed in claim 1, wherein the membrane isless stiff than the frame, to conform with the wearer's facial structurewith minimum force, without a tendency to fold or crease.
 9. A mask forconnection to a wearer's face comprising: a mask body for connectionwith a supply of breathable gas; a cushion, the body and cushiondefining a nose-receiving cavity adapted to receive pressurized gas forbreathing by the wearer in use; at least one securing strap to securethe mask body and cushion to the wearer's head, the strap beingstructured to be tensioned to balance force due to the pressurized gasthat tends to lift the mask off of the wearer's face; and at least onevent opening by which gas expired by the wearer is exhausted toatmosphere; wherein the cushion includes: a frame of resilient materialhaving a rim to surround at least a portion of the wearer's nose; amembrane also of resilient material, said membrane being thinner thanand relatively more flexible than said frame, the membrane being fixedto and extending away from said frame so as to be spaced from said rimby a gap, said membrane having an outer surface forming a facecontacting seal portion that is pre-shaped to generally match thecontours of the wearer's face, wherein the face contacting seal portionis structured such that it is not required to turn in on itself toconform with the wearer's face, in use; wherein: the rim and frame arecurled inwardly towards the nose-receiving cavity and structured toresist deformation so as to form a support structure for the membrane,and said seal portion is resiliently deformable towards said gap to abutsaid rim in use of said mask, depending on the facial contours of thewearer and/or strap tension applied the at least one securing strap; andsaid membrane and said rim each have a co-located notch to accommodatethe bridge of a nose.
 10. A mask as claimed in claim 9, wherein saidmask body includes at least one attachment point to which the at leastone securing strap is coupled.
 11. A mask as claimed in claim 9, whereinsaid membrane is shaped so that said seal portion, in use, contacts atleast the wearer's nose.
 12. A mask as claimed in claim 11, wherein saidseal portion, in use, contacts the facial tissue around the sides andover the bridge of the nose, and between the base of the nose and thetop lip.
 13. A mask as claimed in claim 9, wherein said rim and saidseal portion are shaped to generally match facial contours in the regionof facial tissue around the sides and over the bridge of the nose, andbetween the base of the nose and the top lip.
 14. A mask cushion tosealingly connect a mask to a wearer's face, the cushion comprising: aframe of resilient material having a rim shaped to generally matchfacial contours at least in the region of facial tissue around the sidesof the nose, and between the base of the nose and the top lip; amembrane also of resilient material, the membrane being thinner than andrelatively more flexible than the frame, said membrane being fixed toand extending away from the frame so as to be spaced from the rim by agap, said membrane having an outer surface forming a face contactingseal portion that is pre-shaped to generally match the contours of thewearer's face, the membrane including a pre-formed notch to accommodatethe wearer's nose bridge, wherein the face contacting seal portion isstructured such that it is not required to turn in on itself to conformwith the wearer's face, in use; and wherein the rim and the membrane areinwardly curled in a common orientation towards the wearer's nose inuse, and a strap structured to secure the cushion to the wearer's face,wherein, before application of strap tension, the seal portion is spacedfrom the rim of the cushion by the gap, and as a result of applicationof strap tension and/or to accommodate the wearer's facial contours, theseal portion is resiliently deformable into said gap to abut against therim, said membrane resiliently returning to its original position,spaced from said rim by said gap, when the mask cushion is not in use.15. A mask cushion for sealingly connecting a mask to a patient's faceduring the administration of positive airway pressure, the cushionincluding: a frame of resilient material, said frame having a rim tosurround at least a portion of the patient's face; a membrane ofresilient material and fixed to and extending away from the frame so asto be spaced from the rim, in at least one region of the frame, so as toinclude a gas-filled gap between the membrane and the rim before thecushion is in use, said membrane fully covering or overlying the rim asseen in cross section, wherein each of the rim and the membrane includesa distal end that is unsupported, the distal ends curled inwardly andterminating in a substantially common orientation, a seal formingportion on an outer surface of said membrane, said seal forming portionbeing provided only on said membrane such that only the membrane forms aseal with the patient's face in use; the membrane being pre-shaped togenerally match the contours of the patient's face including a preformedcontoured notch to accommodate the bridge of the patient's nose, whereinthe seal forming portion is structured such that it is not required toturn in on itself to conform with the patient's face, wherein the frameand the membrane at least partly define a breathing cavity to receivepressurized gas for delivery to at least a nasal airway of the patient,the membrane having an aperture comprised to receive the patient's noseand allow the pressurized gas to flow from the breathing cavity to thepatient's nasal airway.
 16. A mask cushion as claimed in claim 15,wherein said seal forming portion is resiliently deformable into the gaptowards the rim in use of the cushion.
 17. A mask cushion as claimed inclaim 15, wherein said rim has a preformed and contoured notch,co-located relative to the notch of the membrane, also to accommodatethe bridge of the patient's nose.
 18. A mask cushion as claimed in claim15, wherein said membrane is shaped so that said seal forming portion,in use, contacts at least a patient's nose.
 19. A mask cushion asclaimed in claim 15, wherein the seal forming portion, in use, contactsthe facial tissue around the sides and over the bridge of the nose, andbetween the base of the nose and the top lip.
 20. A mask cushion asclaimed in claim 15, wherein said rim and said seal forming portion arepre-shaped to generally match facial contours of the facial tissuearound the sides and over the bridge of the nose, and between the baseof the nose and the top lip.
 21. A mask cushion as claimed in claim 15,wherein the frame, the rim and the membrane are formed as a one pieceunit.
 22. A mask cushion as claimed in claim 15, wherein the rim has athickness that is greater than a thickness of the membrane.
 23. A maskcushion as claimed in claim 22, wherein the rim is about four timesthicker than the membrane.
 24. A mask cushion as claimed in claim 22,wherein the rim thickness is about 1.5 mm, and the membrane thickness isabout 0.35 mm.
 25. A mask cushion as claimed in claim 15, furthercomprising a strap structured to secure the cushion to the patient'sface, wherein, before application of strap tension, the seal formingportion is spaced from the rim of the cushion by said gap, and duringapplication of strap tension and/or depending on the patient's contours,the seal forming portion deforms to abut against the rim of the cushion.26. A mask cushion as claimed in claim 15, wherein the membrane isformed of silicone.
 27. A mask cushion as claimed in claim 15, whereinthe membrane is molded.
 28. A mask cushion as claimed in claim 15,wherein the membrane is molded to generally match the contours of thepatient's face even when the mask is not in use.
 29. A mask cushion asclaimed in claim 15, wherein the outer surface of the membrane issubstantially the same shape as the rim of the frame in the at least oneregion.
 30. A mask cushion as claimed in claim 15, wherein the gap isformed between the frame and the membrane in the lip region of thewearer, whereby the membrane may resiliently deform into the gap towardthe frame in use of the cushion.
 31. A mask cushion as claimed in claim15, wherein the rim of the frame is designed to define a maximumdeformation position of the membrane in normal use.
 32. A mask cushionas claimed in claim 15, further comprising a strap structured to securethe cushion to the patient's face, wherein the outer surface forms aseal upon connection to the patient's face and application of minimalforce, if any, to the strap.
 33. A mask cushion as claimed in claim 15,wherein the rim of the frame is approximately 1.5 mm thick.
 34. A maskcushion as claimed in claim 15, wherein the membrane is approximately0.35 mm thick.
 35. A mask cushion as claimed in claim 15, wherein theframe is formed of silicone.
 36. A mask cushion as claimed in claim 15,wherein frame is molded.
 37. A mask cushion as claimed in claim 15,wherein said rim is structured to resist deformation so as to formsupport structure for the membrane.
 38. A mask comprising the maskcushion as claimed in claim 15, said mask including a mask body forconnection with a supply of pressurized breathable gas.
 39. A mask asclaimed in claim 38, wherein the mask further includes at least one ventopening by which gas expired by the patient is exhausted to atmosphere.40. A mask as claimed in claim 38, wherein said mask body includesattachment points.
 41. A mask as claimed in claim 40, further comprisingsecuring straps fixed to said attachment points.
 42. A CPAP treatmentapparatus comprising the mask as claimed in claim 38, the CPAP treatmentapparatus including a flow generator for the supply of gas at a pressureelevated above atmospheric pressure; and a gas delivery conduit coupledto said flow generator.